For removal of arsenic in the aqueous phase, hydrous iron oxides (HIOs) were immobilized in alginate beads with enhanced porosity (designated as HIO-P-alginate beads). The HIO-P-lginate beads had macropores, observed by SEM, as well as mesopores and featured a higher BET surface area than previously developed adsorbent beads. Thus, the adsorption of As(iii) and As(v) by the HIO-P-alginate beads was more rapid than that of previously reported HIO-alginate adsorbents. The kinetics of adsorption were well described by a pseudo-second-order model, indicating that chemisorption mainly governed the As(iii) and As(v) adsorption. We confirmed a chemisorption mechanism for the As(iii) and As(v) adsorption, through isotherm studies using the Dubinin-Radushkevich isotherm model. The application of an intraparticle diffusion model to the kinetic data suggested that the As(v) adsorption onto the HIO-P-alginate beads was controlled entirely by intraparticle diffusion whereas the As(iii) adsorption was governed by intraparticle diffusion only at short contact times. As(iii) adsorption was highest at neutral pH; however, As(v) adsorption was highest at low pH. Both As(iii) and As(v) adsorption did not compete with nitrate adsorption, and the As adsorption improved with increasing ionic strength. The HIO-P-alginate beads could be regenerated several times with a NaOH solution and were successfully reused for arsenic removal.
|Number of pages||10|
|Journal||Environmental Science: Water Research and Technology|
|Publication status||Published - 2018 Aug|
All Science Journal Classification (ASJC) codes
- Environmental Engineering
- Water Science and Technology